TIDE Informe resumido

Algorithms for the semi-automatic extraction of connected tidal channel networks

This result is a technique for the semi-automatic extraction of tidal channel networks from airborne scanning laser altimetry (LiDAR) and high-resolution aerial photography acquired at low tide. The main end-user would be a geomorphologist researching tidal networks. The study of tidal network morphology is important because of the role networks play in tidal propagation and in the evolution of salt marshes and tidal flats. The conventional method of measuring tidal channels is cumbersome and subjective, involving digitising an aerial photograph of the channels and doing field measurement of selected channels. However, LiDAR possesses sufficient spatial resolution to detect even the smallest channels. As LiDAR data are usually collected in conjunction with aerial images, and as aerial photos of inter-tidal zones are presently much more common than LiDAR data, the technique works using either LiDAR data or digital aerial photography alone or with both data sources combined. The algorithm was applied to data gathered at the three study sites used in the TIDE project. The best channel extractions were achieved using LiDAR data. Provided that networks were not too ambiguous, it proved easier to correct the automatically extracted networks than to digitise them manually.